I would like to know about this word, 'weathercock', especially how it ended up with the 2 seemingly different definitions, which I notice frequently happens~one definition that is literal and one that is more figurative.

This is startlingly clear to me now, as in the last 2 years, my 23 year old daughter, who suffered a type of brain injury, is usually only able to think in the literal sense, and I must re-explain every joke, and sometimes whole conversations because of this.

Anyway, I am interested in hearing more about this word, if a column could be done about it, please.

The standard weather vane on barns and other buildings for decades if not centuries contained the image of a rooster, hence "weathercock". Since weathercocks veer in the direction of the wind, it soon came to be used to indicate someone or something that follows the direction of the metaphorical winds, the winds of change.